Control valve mechanism



Oct. 6, 1953 llzyl c. F. BALL ETAL CONTROL VALVE MECHANISM OriginalFiled Feb. 26, 1947 3 Sheets-Sheet l fzrie; 115022. B262202d T17052 Oct.6, 1953 c. F. BALL ETAL 2,654,382

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CONTROL VALVE MECHANISM Original Filed Feb. 26, 1947 s Sheets-Sheet s 6/22 AMJWMI Patented Oct. 6, 1953 UNITED S Pa:.,v assign'ors. toManufactur g G n 'nyn azcorporationrofiPennsylvania Continuation ofabandoned application Serial No. 81],3-74', Match- 9, 1949, whichis adivisionof' application Serial No; 731,126, February 26;- 194'7. 'Ih'iisapplication March-.11); 1952-, Serial:

15 Claims. (01'. 137-102) Qur invention. relates: to improvements in'con;- trolvalve-l mechanisms. Control! valve mechanisms; of the type to:which our invention relates have;particularzutilityinmihevehicles oftheztyne known as: shuttle carsi but: are not confined to suchiuse.

Shuttle cars?" very, commonly have; provision for the supply of powertothein including. a: reel onwhich. a; power cable; is;wound.. Heeldrive-and control means: mustv'be provided so that thereels will wind upcable; when the cars are moving towards the point of. connection, of thecable; to alsourceaofipower'and suchiasito' perm-itlthedrawingtofi: oiitheecablew'hen the; carsare movingaway tromsuch. point of. connection,and also; suchithat, when. the;- carsmovez in. courses or: paths whichinvolve: a need for a shiitingtrom a winding-in. tova payingyoutortromia paving outxtocawinding-in, oi the cable, this: will; beautomatically accomplished. It is also important. that: when: paying outceases,;conditions shall immediately: be established in readiness forawindingeini operation, in order toprevent possibility of the cablesbeing run over, and to prevent an accumulation of slack which might;interfere with the smooth winding oft-he cable. It is further-,-therefore; important to maintain; some. tension. on' the cable even (luring the time when-ritislbeing pulled 01f: of there'el.

A very desirable. apparatus for accomplishing the obj ectives mentionedis described and claimed in our application Serial: N0 731,126; filedFebru va-ry 26; 1947,, for Cable. Reeling Mechanism of which;application this present application i's a divisiom. Thisapparatus, itsillu'straitive form thereishown and. described; includes a pump forsupplyingahydraulicfluid; a-motor-pu-mp device which, the pump suppliesfluid and is 'operatively connected. to the reel sothat whensuclrmotor-pumpl device: operates as a motor it drives the: reel and so:that it is drivenb? the reel whent cable is unwound; together with means'.the improved. valve means of this present case, if the illustrativeeinbodimehtcontrolled'entire 1 y by hydraulicpressuresproducedinthe-normal operations of the device for; imposing on the motor-pumpdevice a substantial pressure, say, for illustration but withoutlimitation thereto, 300 p. s. i. when the reel is being, d'rfi'venin=the winding-in direction; a pressureontheorden, but without limitationthereto, of: 100 p. s; 1. during unwinding of thecable; and apressure,againron the order, but: Without limitation! thereta. oi 30.0 p. Sri'.when the reelis,statienary,,the;latter presr sniebeing automatica ltbimposed uponthe motorr pump device. immediately after a the; reel; comesto rest after an. unwinding operation, Suchvali/ie means also permits;the freedischarge, substantially without any back pressure, of the: fullvolume of fluid: displaced by the pump. wliinthe reel or drum isnotbeing drivenbvthe. motor:- pump; device but is instead driving thelatter as a-pump-andcausing the fluidithen" pumped there. by to bedischarged against a back pressure: im posed upon the motor-pump;device, when. cable is'being drawn: offrthe reel That apparatus includesan; automatic valve mechanismwhich forms. the subject, matter of thisdivisional application, Such automaticlvalve mechanism; includes, in apreferred e bfit iinent, valves operative respectively to determine-thepressure imposed on: the motor-pump; device of such system as isreferred to when the cable is being wounds in; and toideterminethebackpness sure imposed. on-themotor-pump: device. when the cableis;being; unwound, and anautomatic shifter valve controlled: at least inpart, by the pressure built upgby the motor purnpzdevice, when-thesa neis acting as a; pump for shifting; connections, in such a manner thatwheneas, during} winding in ofthe cable the; reliefr device hav ingthehigher setting is in. control, the relief. device having: the lowersetting; shall become operative when cable is to be pulled ofi thereel,v andthernainpump discharge shall then be autoinaticallitrelievedofsubstantially all back pressure; a preierred embodiment there simian beincluded in the means for controlling the osition, of the shifter v,alve. mentioned, arrangements operative to place in conrtol ofth'e'pressure in the Iin'e'between the pump and motorpump device, thepressure relie'fvalve with the liigher'setting, when the reel comes to astop.

In more specific terms; the improved valve means may include; in apreferred embodiment thereof} a-pair oi pressure reliefi va1vessevat:ifferent pressures, at shiftervalve; an a check valve, a supply'passage; a vent passage, and a passage for connection to ad'evi'ce to becontrolled by said valvemeans; the pressu'rerelief 'valve' liaving thehigher-setting having itssuppl'y side 1 stantl y in free communicatihnWit/1 1 said scrapie passage and its discharge side constantly in freecommunication with said vent; said-"check valve also having itssupplysi'zie constantly freewamunication with said supply passage and havihgits: dischargev side; constantly in free communication with saidpassagesforconnection to a device 1701138, controlled;theapressurreliei? valve having the lower setting having itsdischargelsidercomstantly in free communicatiom with: said vent,

and having its supply side connectible with said passage for connectionto a device to be controlled under the control of said shifter valve,and said supply passage connectible with said veiit under the control ofsaid shifter valve, the latter, at its opposite ends subjected to thepressures in said supply passage and in said passage for connection to adevice to be controlled. I

When the pressure in the passage for connection to a device to becontrolled by said "valve 1.

means is less than the pressure the supply passage, the shifter valvemeans is. adapted to interrupt communication between the former passageand the supply side of the pressure relief valve having the lowersetting and between the supply and. vent passages, and upon a pressurein the passage for connection to a device to be controlled by said valvemeans higher than the pressure in the supply passage, said shifter valvemeans is adapted to connect the former passage to the supply side of thepressure relief valve having the lower setting, and to connect thesupply passage to the vent passage.

An object of our invention is to provide an improved controlling valvemechanism. Another object of our invention is to provide an improvedcontrolling valve mechanism including a plurality of selectivelyoperative pressure relief valves and shifter valve means. A furtherobject is to provide an improved control valve including a plurality ofpressure relief valves and a shifter valve hydraulically controlled forthe purpose of rendering one or the other of said relief deviceseffective to control the pressure in a line connectible to a device tobe controlled by said valve means. Yet a further object of our inventionis to provide an improved control valve mechanism including a pluralityof differently set relief devices and a shifter valve constructed andarranged to render one or the other of said relief devices effective tocontrol the pressures in a line to a device to be controlled by saidvalve means, and also to insure control by the relief device having thehigher setting upon cessation of flow through the line connectible to adevice to be controlled by said valve mechanism. Other objects andadvantages of the invention will hereinafter more fully appear.

Referring to the drawings in which one illus- U trative embodiment whichour invention may assume is shown:

Fig. 1 is a diagrammatic view illustrating a control system which wehave chosen as a setting in which to illustrate our improved controlvalve mechanism.

Fig. 2 is an enlarged end view of the control valve mechanism, the viewbeing taken from what might be called the top, if the parts shown inFig. 2 be considered to have the same relationship in space as isindicated on the first figure of the drawings.

Fig. 3 is a view of the control valve mechanism of Fig. 2 viewed fromthe left hand side thereof with the mechanism in the position indicatedin Fig. 1.

Fig. 4 is an enlarged view of the control valve mechanism, showing thesame in the position indicated in Fig. 1.

Fig. 5 is an enlarged sectional view on the plane of the section line 55of Fig. 4.

Fig. 6 is an enlarged sectional view on the plane of the line 6-6 ofFig. 3.

Fig. 7 is a sectional view on the same plane 4 and scale as Fig. 5, withparts shown in different relative positions.

Fig. 8 is a fragmentary section taken on the plane of the line 8--8 ofFig. 5;

Figs. 9 and 10 are views similar to Fig. 1, but showing the controlvalve mechanism in, as it were, developed or schematic views so that allthe passages therethrough and elements thereof may be followed in theirworking operations.

Referring now to the drawings, and first to Figs. 1, 9 and 10, it willbe observed, as a preliminary to the detailed description of the controlvalve mechanism which is the subject matter of this present application,that a source of hydraulic fluid is shown at I, as, for example, asuitably disposed tank, receptacle or sump, to contain the necessaryquantity of hydraulic fluid. The source I is connected by a suitablesuction line 2 with a main pump 3, which is driven from any suitablesource of power, not shown. The pump 3 delivers fluid under pressure toa line 4 which is connected with a valve mechanism 5, which is theparticular subject matter of this application. The valve mechanism 5 hasa connection 6, hereinfter sometimes referred to as a conduit and as aline, with a motor-pump device I operatively connected, as by a belt 8,with a cable reel 9 upon which a power supply cable It is wound. Let ithere be noted again that while our invention is specifically describedwith reference to a control system for a cable reel carrying an electriccable for supplying current to electric motors, the same is not in anysense limited to such systems. The motor-pump device is connected with aconduit H-a vent line-which leads back to the source I, and a reliefline I3 leads from the valve mechanism 5 to the line H. The pump 3 isshown as of the intermeshing gear type, as is also the motor-pump device1.

The valve mechanism 5 includes a supply chamber I6 to which hydraulicfluid is delivered by the conduit 4. From this chamber fluid may bedelivered through a shifter valve chamber I! back to the connection 13leading to the source I, or, as will shortly be described, to anotherchamber i8 which is connected with the conduit 6 leading to the deviceto be controlled, as illustrated to the motor-pump device 7, and theconduit 6 communicates also with the shifter valve chamber 11, as laterdescribed.

Desirably, the chambers I6 and I8 may be formed in line with each other,as shown in Figs. 5 and 7, and separated by a -ported septum 20, whichforms a valve seat 2|, with which a check valve 22 is adapted tocooperate and against which said check valve is adapted normally to bemaintained by a spring 23, which at one end rests against the checkvalve and at its other end rests upon a plug 24 with which the conduit 6is threadedly or otherwise suitably connected. The structure of thischeck valve 22 may be seen from Fig. 8; and it will be noted that thisvalve has a number of slots 25 in its periphery through which fluid mayflow from the chamber Hi to the chamber 18 when the valve 22 isunseated. The supply or upstream side of the check valve communicatesfreely with the supply chamber I6 and its discharge or downstream sidefreely with the conduit 6.

Theshifter valve receiving chamber Il includes five annular chambers,each spaced from the next adjacent chamber by a ported partition. Theseannular chambers, starting from the top in Fig. 5, are numberedrespectively 26, 21, 28, 29 and 30. A ported partition 3| separates thechambers 26 g ate-see and "21". A ported" partition 32' separates thechambers and 26. Similarly, ported partitions 33 and 34 respectivelyseparate the chambers 26 and 2e and the chambers 29 and 36. Each of theported partitions has the port therethrough of the same size 'as'each ofthe others, and these several ports are coaxially'arranged so that theirsurrounding walls provide guidance for a spooltype ordoublehead'edshifter valve 36- comprising an upperhollowhead 3'1 and alower head 38, a connecting portion 3 9 of reduced cross section whosepresence: resultsin the provision between the, adjacent surfaces of saidheads of an annular fluid conducting groove or conduit 4-0, and a stopprojection 4|. The head 31, as indicated, has a recess 42 therein intowhich extends a spring 43 whose upper end in Fig. 5" contacts anabutment plug-4'4 suitablypacked at 45' to prevent leakage. A passage4610f relatively small diameter atits lower end 4-! extends from thechamber 42 through the stop portion 41 of the valve 36. The stop portionof the valve is adapted to cooperate with a suitable abutment plug 48.

The annular chamber 26 communicates with the-supply chamber l6 through aport or cored openings!) (whethera bored port or a cored opening'dependingon whether the valve casing is machined fromthe solid or cast).Similarly, the annular space 21 communicates as at 5| with the chamberl6. The annular chamber 28 communic'ates through the conduit I3 with theconduit H leading to the source I. The annular chamber' 29 communicatesthrough a port or opening 52 with a chamber 53 in a relief valve casing54 shown in the drawings as a separate element from themainbody ofthe'valveinechanism as a whole, but obviously fo'rmable with it as aunit if desired. The annular space 30 communicates an opening 55 withthe chamber l8. The

annular chamber 28 also communicates through The annular chamber 26*communicates through an opening 6| with a chamber 62 in the reliefvalve housing 58. The chamber 53 is separated from the chamber 60 by aported valve seat 6'4 with which a spring pressed relief valve 65' isadapted to cooperate. A spring 66 having a follower 61' adjustablyloaded by an adjusting screw and nut mechanism 68 controls thecompression of the spring 6.6, and thus determines the pressure at whichthe valve 65 will lift from the seat 64.. The chamber 53 is at theupstream side of the valve 65, the chamber 60 at its downstream side. Avalve seat 69 surrounding a port extending between the chambers 51 and62 is adapted to. cooperate with a relief valve 1- t pressed in aclosing direction by a spring 12 which rests against a follower 1-3whose position may be adjus'ted. by suitable screw and nut mechanism 14.The chamber 62 is at the upstream side of valve TI, the chamber 51 atits downstream side. It will be noted that when the valve 36. is intoprposition, it does not prevent communication between the chamber [6and the port 10. The normal compression of the spring 12 will be muchhigher than the normal compression of the spring 66 when they arecontrolling valves having equal areas subjected to pressures tending tounseat such valves. For example, it may require a liquid pressure of 300p. s. i. in chamber 62 to unseat valve H while, for example, a pressureof 1,00

p. s. i. in chamber 53 will suflice to unseat'valve 65.

The pump 6 maybe-considered, for the purpose of describing the mode ofoperation of-the embodiment of our invention which has 'beene'xplainedabove, to be driven continuously while the vehicle is in use;Accordingly, it is takingin liquid from thesource t through the conduit2 and discharging it through the-conduit Mute-the chamber f6, and thenumso delivered to the chamber 66' must go some'where. Obviously, fromwhat has beensaid, the fluid when conditions-are such that the cable canbe wound in,'may= at least in part go-past the check valve 22 andthrough the conduit 6 and into thamotor-pumpdevice-1' and drive thelatter in "a direction tociiec't winding-i-n of the cable 16, and thenpass back-to the source 1 throughthe conduit H. Because the rate ofwinding-inof the cable'will be controlled by the rate at which thevehicle moves in the direction in which the cableextends, it will beevident that all oftheliquid pumpedby thepump 3' cannot pass throughthe: motor pumpadevice; 1?, underordinary circumstances, atv least, andac, cordingly prov-isionis made for the return of the excess liquiddischarged by the pump 3 to the line H through the connection [3.As'considerable power must beexerted by the motonpump device 1 to effectwinding-in of the cable: at; the desired maximum. rate, the excess fluidmust. not be allowed to pass through the connection: 131-50 readily thatthe necessary pressure. will not: be maintained in the supplyconnection. 6 to the motor-pump device 1:.Acccrdinglyyasabove-indicated, the compression of the'spring 12 whichcontrols the relief valve T l will be made su-flicient to compel thedesired pressure, to; bemaintai-ned in the chamber l'fi'and'in theconduit 6. For example, a pressureofwup. s. i.;may beymaintained in the.fluid supply connections to the motor pump device I by the appropriatesetting of the spring T2. It will be noted that from the chamber 16 theport 50 opens into the annular chamber 25 and that the, shifter; valve36 can never shutoff communication through the chamber 26 between theport. 56 and the opening 6|, and accordingly that whenever the pressurein the port 1-6 is; high enou'g-hto unseat: the relief valve 1| fluidmavpass into. the chamber 51 and through the'port'56, and, referring; toFigs. 6 and '7, through the chamber 26120 the conduit l3 and so backtothe source, I by way of theconduit H. In Figs. 9. and, 10,-becauseofthe desirability of avoiding overlapping ports, the connection ofthe-conduit. 43 with. the chamber 28 is shown as made via a portionoi-the conduit 56 instead of opening into the chamber 26 separately fromthe port 56 and. at right angles to the communication of that portwiththechamber 28. Fig. 10., subject tothe understandingjust expressedimaybe considered to show the normal position of the parts during the.operation of the motor-pumpdevi'ce I a direction to efliect winding-inof thecable 16;- in other words, the mode of operation which occurs whenthe vehicle is moving in a direction to shorten'the free length of thecable. It will be observed-that theshitter valve 36 occupies at thistimethe position shown in Figs. 5, 6 audit), being so; heldby reasonvofthe fact that the hydraulic pressurecnits lower end is: less thanthe-hydraulic pressurev onitsupper end by'theamount occasionedbythepresence of the spring 23 and'that, moreover, the spring operatesto hold the shifter valve 36 in the position mentioned.

Let it now be supposed that the vehicle brought to'a stop. This willmean that'the' motor= pump device 1 will no longerdrive the reel toconduit 6.

7 wind in'the cable, but nothing will occur in the controlling apparatuswhich will result in a movementof this shifter valve 36 to reduce thepressure imposed on the motor-pump device I, and so the cable tensionwill be maintained undiminished when the vehicle is at a standstill.

Suppose now that the vehicle is caused to move in a direction which willnecessitate the unwinding of the cable from the reel in order for suchmotion to take place. The motor-pump device I will then be driven in theopposite direction, and initially against the full pressure maintainedby the setting of the relief valve device I I. However, the instant thatthe motor-pump device commences to draw fluid from the source I throughthe conduit l and to discharge into the conduit 6, the valve 22 willseat, and the only passage for flow of the fluid which can beestablished will be one opened by upward movement of the shifter valve36 to the position shown in Figs. 7 and 9; and, because the pressurewhich will be built up momentarily may be in excess of the pressureimposed by the pump 3, which cannot exceed 3-00 p. s. i., or whateverother selected pressure may be fixed by the relief valve mechanism 7!,the valve 36 will move upward to the position mentioned. When thisoccurs the fluid pumped by the main pump 3 will pass from the chamber l5through the port 5i into the chamber 27, through the groove between theheads of the shifter valve into the chamber 28, and freely through theconduits i3 and ii back to the source. Note that the back pressure onthe main pump 3 has been completely removed except for such pressure asfriction of the liquid in the passages may involve. Upward movement ofthe shifter valve 36 will also open a passage from'the chamber 3%] tothe chamber 29, and, when the valve 65 is unseated, through the chamber60 and port 59 to the chamber 28 and through the latter and by way ofthe conduits l3 and HI back to the source. The valve 65 is unseated at amuch lower pressure, as above indicated, than the valve l I, say, at apressure of 100 p. s. i. in the chamber 53, and accordingly the tensionon the cable I!) will be substantially reduced and the reel may beturned backwards, driving the motorpump device 1 as a pump, with a muchlower pressure in the line b than during the operation of the motor-pumpdevice as a motor.

Now let it be assumed that the vehicle stops. The motor-pump device nolonger acts as a pump and no longer delivers fluid through the Thepassage 45, 5! permits equalization of pressures at the opposite ends ofthe shifter valve 36 practically immediately, and the spring forces theshifter valve back to the position shown in Figs. 5, 6 and 10. Thisinterrupts communication between the passages 52 and 55 and between thechamber and the conduit 13. Accordingly the pressure of the fluid in theline 6 and chamber l6 will build up to the value at which the reliefvalve H will be unseated. Therefore it will be evident that when thevehicle comes to a'stop conditions will automatically result which willcause the motor-pump I to be subjected to the higher pressure necessaryfor most efiicient winding in operations when the vehicle commencestomove in the direction where winding-in of the cable is needed. Indeedthe cable tension will be immediately increased,

From the foregoing description, it will be evident that we have providedan improved automatic control valve mechanism in which a shifter valve,automatically controlled, places differently set relief valves incontrol of the. critical pres-i sure in accordance with differentoperations of the apparatus controlled and is adapted automatically toprovide a free discharge for the normal operating fluid when it is notbeing used for motor actuation, thereby reducing power and avoidingexcessive heating.

More specifically, the improved valve means will be noted to include apair of pressure relief valves set at different pressures, a shiftervalve, and a check valve, a supply passage, a vent passage, and apassage for connection to a device to be controlled by the valve means,the pressure relief valve with the higher setting, and the check valveeach having its supply side constantly in free communication with thesupply passage, the two pressure relief valves each having theirdischarge sides in free communication with said vent, the pressurerelief valve with the lower setting having its supply side connectiblewith the passage for connection to a device to be controlled and thesupply chamber connectible to the vent, both under the control of theshifter valve, and the shifter valve having opposed areas subjected tosupply chamber pressure and to the pressure in the passage forconnection to a device to be controlled, whereby when the pressure insaid latter passage is less than the pressure in the supply passage theshifter valve will interrupt communication between the latter and thevent and between the supply side of the relief valve having the lowersetting and the passage connectible to a device to be controlled, andwhen the pressure in the latter passage exceeds supply chamber pressure,the shifter valve means connects such passage to the supply side of therelief valve having the lower setting and the supply chamber to thevent. In certain of the claims the passage for connection to a device tobe controlled by the valve mechanism, which passage is connected by theconduit 6 to the motor-pump device I, is referred to, i. e., is defined,for brevity, as a work passage.

This application is a continuation of our copending application Ser. No.80,374, filed March 9, 1949, now abandoned, which in turn is a divisionof our copending application Ser. No. 731,126, filed February 26, 1947.

While there is in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

We claim:

1. In combination, in a valve mechanism, a casing providing chambershaving in them respectively a shifter valve, two relief valves, and acheck valve, an external inlet connection having communication with oneend of said shifter valve containing chamber and also with said chamberat a point between the ends of the latter and also with said check valveand with one of said relief valves, an external vent connectioncommunicating with the chambers containing each of said relief valvesand with said shifter valve chamber at a different point between theends of the latter, a connection between the other relief valve and saidshifter valve chamber at still a difierent point therein, and a thirdexternal connection communicating with the other end of said shiftervalve chamber and with said check valve chamber.

2. In combination, .in -:a valve mechanism, a casing providing chambershaving in them .re- .spectively a shifter valve, two relief valves having different settings, and a check valve, an external inlet connectionhaving communication with one end of said shifter valve containingchamber and also with said chamber at a point between the ends of thelatterand also with said check valve and with one of said relief valves,an external vent connection communicating with thechamberscontainingeach of said relief valves and with said shifter valvechamber :at a second and different point between the ends of the latter,a connection between the other relief valve and said shifter valvechamber at a third point between the ends of the latter, and a thirdexternal connection communicating with the other-end of said shiftervalve chamber and with said check valve chamber, said third point beingnearer said other end of said shifter valve chamber than said secondpoint is.

3. In combination, in a valve mechanism, casing means providing chambersincluding a shifter valve chamber and two relief valve chambers, asupply chamber, and a check valve chamber, a shifter valve in saidshifter valvechamber, relief valves, having different loadings, in saidrelief valve chambers, a check valve in said check valve chamber, meansplacing said supply chamber in communication with a connection at theexterior of said casing means, means establishing communication betweensaid check valve chamber and a'connection at the exterior of said casingmeans, means establishing communication between an intermediate point insaid shifter valve chamber and a connection. at the exterior of saidcasing means, means establishing communication between said supplychamber and one end of said shifter valve chamber, means establishingcom munication between said check valve chamber and the other end ofsaid shifter valve chamber, means establishing communication betweeneach of said relief valve chambers and the exterior of said casingmeans, means establishin communication between said supply chamber andthe seat end of one of said relief valve chambers, means forestablishing communication between the supply chamber and the seat endof said check valve chamber, means establishing communication be tweensaid shifter valve chamber and the seat end of the other of said. reliefvalve chambers; and means establishing another communication supplychamber, and in alinement with said sup ply chamber, a check valvechamber, a shifter valve in said shifter valve chamber, relief valves,-

having different loadings, in said relief valve chambers, a check valvein said check valve chamber, means placing said supply chamber incommunication with a connection at the exterior of: said casing means,means establishing communication between said check valve chamber and,aconnection at theexterior of said casing means, means establishingcommunication between an intermediate point in said shifter valvechamber and a connection at theexterior of said casing means, meansestablishingcommunica--- tion between said supply chamber and one end ofsaid shifter valve chamber, means establishing communication betweensaid check valve cham ber andthe-otherend of said'shifter valve chamher,means establishing communication between each of said reliefvalve-chambers and the ex-- terior of said casing means, meansestablishing communication between said supply chamber and the seat endcr me of said relief valve chambers, means for establishingcommunication between the supply chamber and the seat of said checkvalve chamber, means establishing com- -munication between said shiftervalve chamber and the seatend of the other of said relief valvechambers, and means establishing another communication between saidsupply chamber and said shifter valve chamber, said shifter valve havingthereon portions bounding a fluid conduit and in one extreme positionthereof connecting through said conduit said means establishing anothercommunication between said supply cham: her and said shifter valvechamber and said means establishing communication between anintermediate point in said shifter valve chamber and 'a connection atthe exterior of said casing means.

5. In combination, in a valve mechanism, cas ing means providingchambers including a shifter valve chamber and two relief valvechambers, a supply chamber, and a check valve chamber, a shifter valvein said shifter valve chamber,- relief valves, having differentloadings, in said relief valve chambers, a check valve in said checkvalve chamber, means placing said supply chamber in communication with aconnection at the exterior of said casing means, means establishingcom"- munication between said check valve chamber and a connection atthe exterior of said casing means, means establishing communicationbetween an intermediate pointin said shifter valve chamber and aconnection at the exterior of said casing means, means establishingcommunication between said supply chamber and one end of said shiftervalve chamber, means establishing communication between said check valvechamber and the other end of said shifter valve chamber, meansestablishing communication between each of said relief valve chambersand the exterior of said casing means, means establishing communicationbetween said supply chamber and the seat end of one of said relief valvechambers, means for establishing communication between the supplychamber and the'seat-end of said check valve chamber, means establishingcommunication between said shifter valve chamber and the seat end of theother of said relief valve chambers, means establishing anothercommunication between" said supply chamber and said shifter valvechamber, and means for biasing said shifter valve towards one end of itschamber.

6. In combination, in a valve mechanism,

casing means providing chambers including a;

shifter valve chamber and two relief valve chambers, a supply'chamber,and a check valve chamber, a shifter valve in said shifter valvechamber, relief valves, having different loadings, in said reliefvalvechambers, a check valve-insaid check valvechamber, means placingsaid supply chain her in communication with a connection at the exteriorof said casing means, means establishihg communication between saidcheck valve chamber and a connectionat-the exterior of said casingmeans, means establishing communication between an intermediate point insaid shifter valve chamber and a connection at the exterior of saidcasing means, means establishing communiend of said shifter valvechamber, means establishing communication between said-check,-

11 valve chamber and the other end of said shifter valve chamber, meansestablishing communication between each of said relief valve chambersand the exterior of said casing means, means establishing communicationbetween said supply chamber and the seat end of one of said relief valvechambers, means for establishing communication between the supplychamber and the seat end of said check valve chamber, means establishingcommunication between said shifter valve chamber and the seat end of theother of said relief valve chambers, means establishing anothercommunication between said supply chamber and said shifter valvechamber, means for biasing said shifter valve towards one end of itschamber, and means for providing a restricted communication between theopposite ends of said shifter valve chamber.

'7. In combination, in a valve mechanism, casing means providingchambers including a shifter valve chamber and two relief valvechambers, a supply chamber, and a check valve chamber, a shifter valvein said shifter valve chamber, relief valves, having different loadings,in said relief valve chambers, a check valve in said check valvechamber, means placing said supply chamber in communication with aconnection at the exterior of said casing means, means establishingcommunication between said check valve chamber and a connection at theexterior of said casing means,;means establishing communication betweenan intermediate point in said shifter valve chamber and a connection atthe exterior of said casing means, means establishing communicationbetween said supply chamber and one end of said shifter valve chamber,means establishing communication between said check valve chamber andthe other end of said shifter valve chamber, means establishingcommunication between each of said relief valve chambers and theexterior of said casing means, means establishing communi cation betweensaid supply chamber and the seat end of one of said relief valvechambers, means for establishing communication between the supplychamber and the seat end of said check valve chamber, means establishingcommunication between said shifter valve chamber and the seat end of theother of said relief valve chambers, means establishing anothercommunication between said supply chamber and said shifter valvechamber, means for biasing said shifter valve towards one end of itschamber, and means for providing a restricted communication between theopposite ends of said shifter valve chamber, said shifter valve soconstructed and the connections with its chamber so arranged that inop-- posite positions of said shifter valve said supply chamber isrespectively connected by said shifter valve with the exterior'of saidcasing means and cut off from such communication except past one" ofsaid relief valves.

8. In combination, in a valve mechanism; casing means providing chambersincluding a shifter valve chamber and two relief valve chambers, asupply chamber, and a check valve chamber, a shifter valve in saidshifter valve chamber,

relief valves, having different loadings, in said relief valve chambers,a check valve in said check valve chamber, means placing said supplychamber in communication with a connection at the exterior of saidcasing means, means establishing communication between said check valvechamber and a connection at the exterior of said casing means, meansestablishing communication between an intermediate point in said shiftervalve chamber and a connection at the exterior of said casing means,means establishing communication between said supply chamber and one endof said shifter valve chamber, means establishing communication betweensaid check valve chamber and the other end of said shifter valvechamber, means establishing communication between each of said reliefvalve chambers and the exterior of said casing means, means establishingcommunication between said supply chamber and the seat end of one ofsaid relief valve chambers, means for establishing communication betweenthe supply chamber and the seat end of said check valve chamber, meansestablishing communication between said shifter valve chamber and theseat end of the other of said relief valve chambers, means establishinganother communication between said supply chamber and said shifter valvechamber, means for biasing said shifter valve towards one end of itschamber, and means for providing a restricted communication between theopposite ends of said shifter valve chamber, said shifter valve soconstructed and the connections with said shifter valve chamber soarranged that in opposite positions of said shifter valve said checkvalve chamber is respectively placed in communication with one of saidrelief valves and cut off from such communication.

9. In combination, in a valve mechanism, casing means providing chambersincluding a shifter valve chamber and two relief valve chambers, a

supply chamber, and a check valve chamber, a

shifter valve in said shifter valve chamber, relief valves, havingdifferent loadings, in said relief valve chambers, a check valve in saidcheck valve chamber, means placing said supply chamber in communicationwith a connection at the exterior of said casing means, meansestablishing'communication between said check valve chamber and aconnection at the exterior of said casing means, means establishingcommunication between an intermediate point in said shifter valve end ofone of said relief valve chambers, means for establishing communicationbetween the sup ply chamber and the seat end of said check valvechamber, means establishing communication between said shifter valvechamber and the seat end, of the other of said relief valve chambers,means establishing another communication between said supply chamber andsaid shifter valve chamber, means for biasing said shifter valve towardsone end of its chamber, and means for providing a restrictedcommunication between the opposite ends of said shifter valvechambensaid shifter valve so constructed and the connections with saidshifter valve chamber so arranged that in opposite positions of said.shifter valve said supply chamber is respectively connected by saidshifter valve with the exterior of said casing means and cut off fromsuch communication except past one of said relief valves and said checkvalve chamber is respectively connected with the other of said reliefvalves and cut off from such communication. j

10. In combination, in a valve mechanism, a

pair of pressure relief 'va'lves'setat different'pressures, a shiftervalve, and a check valve; a' supply passage, a. vent.' passage, and awork passage for connection to aideviceto be controlled, means forcontinuously connecting the supply side of the pressure relief valvevhaving the. higher. setting in free communication with the supplypassage and the dischargeside. of the pressure. reliefi'valve having thehigher setting continuously in free com: munication with the ventpassage, means forconnecting the. supply side ofsaid check valvecontinuously, in free communication with the supply passage and forcontinuously connecting the discharge side of said check valve in freecommunication with the work passage, means for continuously connectingthe discharge side of the pressure relief valve having the lower settingin free communication with said vent passage, means controlled by saidshifter valve for connecting the supply side of said pressure reliefvalve having the lower setting with the work passage, means controlledby said shifter valve for connecting said supply passage with said ventpassage, and means for subjecting the opposite ends of said shiftervalve respectively to the pressure in the supply passage and to thepressure in the work passage.

11. In combination, in a valve mechanism, a pair of pressure reliefvalves set at different pressures, a shifter valve, and a check valve, asupply passage, a vent passage, and a work passage for connection to adevice to be controlled, means for connecting the supply sides of thepressure relief valve with a higher setting and the check valveconstantly in free communication with the supply passage, means forconnecting the discharge sides of the two pressure relief valvesconstantly in free communication with the vent passage, passage meansfor connecting the supply side of the pressure relief valve with thelower setting with the work passage and for connecting the supplypassage to the vent passage, both under the control of the shiftervalve, said shifter valve having opposed areas facing longitudinallythereof, and means for subjecting one of said areas to the supplypassage pressure and the other to the presure in the work passage,whereby, when the pressure in said latter passage is less than thepressure in the supply passage the shifter valve will be moved in onedirection, and when the pressure in the work passage exceeds supplypassage pressure the shifter valve will be moved in the oppositedirection, said shifter valve controlled passage means so arranged thatin the first mentioned position of the shifter valve such valve willinterrupt communication between the supply passage and the vent passageand between the supply side of the relief valve having the lower settingand the work passage, and in the second position of the shifter valvethe latter will connect the work passage to the supply side of therelief valve having a lower setting and connect the supply passage tothe vent passage.

12. In combination, in a valve mechanism, a pair of pressure reliefvalves, a shifter valve, and a check valve a supply passage, a ventpassage, and a work passage for connection to a device to be controlled,means for continuously connecting the supply side of one of saidpressure relief valves in free communication with the supply passage andthe discharge side of said same pressure relief valve continuously infree communication with the vent passage, means for connecting thesupply side of said check valve continuously in free communication withthe supply passage and continuously connecting the discharge side ofsaidc'heck valve in free communication with the work passage, means forcontinuously connecting the discharge side'of the other pressure reliefvalve in free communication with the-vent passage; means controlled"bythe shifter-valve'for connecting the supply side ofsaid'last'mentioned pressure relief valve with the-workpassag-e,meanscontrolled by the shifter valve fer connec-ting" the supply passage withthe vent passage, and'means for-subjecting-the opposite ends oftheshifter valve respectively to-the pressure in the 'suppl-y passageand to-the pressure in the work passage.

13. In combination, in a valve mechanism, a pair of pressure reliefvalves set at difierent pressures, a shifter valve, and a check valve,2. supply passage, a vent passage, and a work passage for connection toa device to be controlled, means for continuously connecting the supplyside of one of said pressure relief valves in free communication withthe supply passage and the discharge side of said same pressure reliefvalve continuously in free communication with the vent passage, meansfor connecting the supply side of said check valve continuously in freecommunication with the supply passage and continuously connecting thedischarge side of said check valve in free communication with the workpassage,

means for continuously connecting the discharge side of the otherpressure relief valve in free communication with the vent passage, meanscontrolled by the shifter valve for connecting the supply side of saidlast mentioned pressure relief valve with the work passage, meanscontrolled by the shifter valve for connecting the supply passage withthe vent passage, means for subjecting the opposite ends of the shiftervalve respectively to the pressure in the supply passage and to thepressure in the work passage, and means for providing a restrictedcommunication between the opposite ends of said shifter valve.

14. In combination, in a valve mechanism, a casing providing a chamberhaving in it a fluid thrown shifter valve, said casing having associatedwith it a first and a second relief valve and a check valve each havingan upstream and a downstream side, a fluid inlet having connections withthe upstream side of said check valve and of said first relief valve, aconnection with said shifter valve chamber controllable by said shiftervalve and a connection for transmitting fluid for throwing said shiftervalve in one di rection, an external vent connection for said shiftervalve chamber connectible by said shifter valve with the first mentionedconnection with said shifter valve chamber, connections for conductingto vent fluid from the downstream sides of both of said relief valves, aconnection between the upstream side of said second relief valve andsaid shifter valve chamber at a point alternatively covered anduncovered by said shifter valve, and an external connectioncommunicating with the downstream side of said check valve chamber andhaving a connection for transmitting fluid for throwing said shiftervalve oppositely to said first direction.

15. In combination, in a valve mechanism, a casing providing a shiftervalve chamber containing a shifter valve, and having associated with ittwo relief valves and a check valve each having an upstream and adownstream side, a fluid supply connection communicating with theupstream side of said check valve and of one of said relief valves andfurther communicating with said shifter valve chamber both at one end ofthe latter and at a point spaced from such end but between the two endsof said shifter valve chamber, a vent connection communicating with saidshifter valve chamber at a point between the ends of the latterdifierent from the valve and said shifter valve chamber at a point 10 inthe latter between its ends and different from each of said other twopoints, and a work connection communicating with the other end of 16said shifter valve chamber and with the down.- stream side of said checkvalve.

CHARLES '1. BALL. RICHARD T. HAIR.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,395,302 Slomer Feb. 10, 1946 2,474,122 .Schneck June 21,1949 2,477,669 Stephens Aug. 2, 1949

